THE EFFECTS OF CADMIUM ON THE GILLS OF THE GOLDFISH CARASSIUS-AURATUS L - METAL UPTAKE AND HISTOCHEMICAL-CHANGES

1. Uptake of cadmium and histochemical changes of mucopolysaccharides and of cytochrome-oxidase in the gill epithelium of Carassius auratus were examined at different times after 10 ppm Cd2+ exposure in hard water (520 mg/l CaCO3). 2. All animals survived treatment and no significant behavioural changes were observed. 3. Cd2+ precipitates completely as CdCO3 in the first 72 hr. Nevertheless, metal uptake in the organ was observed beyond this period. 4. After 96 hr an increase in the amount of sulphate mucins and a reduction in intensity of the cytochrome-oxidase reaction were observed. 5. Cadmium toxicity in very hard water is interpreted as being due to CdCO3 ingestion which might cause histochemical alterations in the gills.